The present technology relates to a storage controlling apparatus, a memory system, an information processing system and a storage controlling method. Particularly, the present technology relates to a storage controlling apparatus, a memory system, an information processing system and a storage controlling method for controlling a non-volatile memory.
In information processing systems in recent years, a non-volatile memory (NVM) is sometimes used as an auxiliary storage apparatus or a storage. Such non-volatile memories are roughly divided into a flash memory ready for data accessing in a great size as a unit and a non-volatile random access memory (NVRAM) with which high-speed random accessing can be carried out in a small unit. Here, as a representative example of the flash memory, a NAND type flash memory is available. On the other hand, as an example of the non-volatile random access memory, a ReRAM (Resistance RAM), a PCRAM (Phase-Change RAM), a MRAM (Magnetoresistive RAM) and so forth are available.
The non-volatile memories described above include a memory in which rewriting of a bit of one of binary values and rewriting of the other one of the binary values are carried out in order in a writing process. In such a non-volatile memory such as, for example, the ReRAM, the maximum value of power consumption in each rewriting increases as the number of bits to be rewritten increases. In order to reduce the maximum power consumption, a semiconductor device has been proposed in which that one of inverted write data and non-inverted write data which includes a smaller number of bits to be rewritten is selected and the selected write data is written into a non-volatile memory. A semiconductor device of the type described is disclosed, for example, in PCT Patent Publication No. 2006/106577.
The semiconductor device described above reads out data already written at an address of a writing destination and retains the read out data into a buffer. Then, the semiconductor device inverts write data and further retains the write data before and after the inversion into the buffer. The semiconductor device compares the write data before and after the inversion with the read out data, and writes that write data which indicates a smaller number of changing bits from between the write data before and after the inversion. If the changing bit number decreases by writing of the inverted data, then the maximum value of the power consumption reduced.